AS3碰撞检测类
众所周知，Adobe有一群懒散的工程师，所以adobe给as3提供的一些工具方法也就很具有欺骗性，今天我要给大家提供的是一个非常常用的功能。
碰撞检测，无论是游戏还是什么，都是很常见的，flash.display包下面的Display类中有个hitTestObject()的一个方法，简言之，这个东西检测矩形元件检测还不错，但是有多少图形是标准的矩形呢？所以今天我要给大家推荐一个很好的碰撞检测类：
package {import flash.display.BitmapData;import flash.display.BlendMode;import flash.display.DisplayObject;import flash.display.Sprite;import flash.geom.ColorTransform;import flash.geom.Matrix;import flash.geom.Point;import flash.geom.Rectangle;public class HitTest{public static function complexHitTestObject( target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1 ):Boolean{trace(complexIntersectionRectangle( target1, target2, accurracy ).width);return (complexIntersectionRectangle( target1, target2, accurracy ).width != 0);}public static function intersectionRectangle( target1:DisplayObject, target2:DisplayObject ):Rectangle{if( !target1.root || !target2.root || !target1.hitTestObject( target2 ) ) return new Rectangle();var bounds1:Rectangle = target1.getBounds( target1.root );var bounds2:Rectangle = target2.getBounds( target2.root );var intersection:Rectangle = new Rectangle();intersection.x = Math.max( bounds1.x, bounds2.x );intersection.y = Math.max( bounds1.y, bounds2.y);intersection.width = Math.min( ( bounds1.x + bounds1.width ) - intersection.x, ( bounds2.x + bounds2.width ) - intersection.x );intersection.height = Math.min( ( bounds1.y + bounds1.height ) - intersection.y, ( bounds2.y + bounds2.height ) - intersection.y );return intersection;}public static function complexIntersectionRectangle( target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1 ):Rectangle{ if( accurracy <= 0 ) throw new Error( "ArgumentError: Error #5001: Invalid value for accurracy", 5001 );if( !target1.hitTestObject( target2 ) ) return new Rectangle();var hitRectangle:Rectangle = intersectionRectangle( target1, target2 );if( hitRectangle.width * accurracy <1 || hitRectangle.height * accurracy <1 ) return new Rectangle();var bitmapData:BitmapData = new BitmapData( hitRectangle.width * accurracy, hitRectangle.height * accurracy, false, 0x000000 ); bitmapData.draw( target1, HitTest.getDrawMatrix( target1, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, -255, -255, 255 ) );bitmapData.draw( target2, HitTest.getDrawMatrix( target2, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, 255, 255, 255 ), BlendMode.DIFFERENCE );var intersection:Rectangle = bitmapData.getColorBoundsRect( 0xFFFFFFFF,0xFF00FFFF );bitmapData.dispose();if( accurracy != 1 ){intersection.x /= accurracy;intersection.y /= accurracy;intersection.width /= accurracy;intersection.height /= accurracy;}intersection.x += hitRectangle.x;intersection.y +=( hitRectangle.y);return intersection;}protected static function getDrawMatrix( target:DisplayObject, hitRectangle:Rectangle, accurracy:Number ):Matrix{var localToGlobal:Point;;var matrix:Matrix;var rootConcatenatedMatrix:Matrix = target.root.transform.concatenatedMatrix;localToGlobal = target.localToGlobal( new Point( ) );matrix = target.transform.concatenatedMatrix;matrix.tx = localToGlobal.x - hitRectangle.x;matrix.ty = localToGlobal.y - hitRectangle.y;matrix.a = matrix.a / rootConcatenatedMatrix.a;matrix.d = matrix.d / rootConcatenatedMatrix.d;if( accurracy != 1 ) matrix.scale( accurracy, accurracy );return matrix;}}}